You think kind of like me. I separate guitar tone into 3 different aspects. Attack - bloom of note - decay or commonly accepted as sustain I also tend to look at things a bit more like Tesla did outside of his electricity experiments. In regards to a pickup it is all about the string reacting within the field but everything has acoustic properties based on reflection and absorption. These properties directly effect sustain or decay of a note and frequencies enhanced or manipulated by certain woods. He viewed the world as a place of acoustic resonance and I firmly agree. Granted a guitar string is going to produce a certain tone it's the end result in a very dense trade off of material traits the string is attached to. Technically more of an energy and heat trade of once broken down to atomic levels but that's a little too far for the scope of this thread.